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Updated: Feb 22, 2026

Clinical Imaging of Microwave Mammography

Clinical Imaging of Microwave Mammography

Published on: November 14, 2025

Design of current source for multi-frequency simultaneous electrical impedance tomography.

Bing Han¹, Yanbin Xu¹, Feng Dong¹

¹Tianjin Key Laboratory of Process Measurement and Control, School of Electrical and Information Engineering, Tianjin University, Tianjin, People's Republic of China.

The Review of Scientific Instruments

|October 2, 2017

Summary

A novel field programmable gate array-based current source enhances multi-frequency electrical impedance tomography (MFEIT) systems. This precise, wideband current source improves image reconstruction accuracy for time-varying biological applications.

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Area of Science:

Biomedical Engineering
Electrical Engineering
Medical Imaging

Background:

Multi-frequency electrical impedance tomography (MFEIT) is advancing towards simultaneous multi-frequency measurements for faster, time-varying biological imaging.
Accurate and stable current sources are critical for high-quality MFEIT image reconstruction.

Purpose of the Study:

To develop and evaluate a field programmable gate array (FPGA)-based current source for MFEIT systems.
To enhance the accuracy and stability of current injection in MFEIT.

Main Methods:

A novel current source circuit was designed using a feedback amplifier (AD844) and differential topology.
Optimal phase offsets for harmonic sinusoids were determined via crest factor analysis.
Performance was validated through simulation, actual measurement, and biological RC model experiments.

Main Results:

The proposed current source demonstrated comparable or superior output impedance to the Howland pump, especially at high frequencies, with lower resistor tolerance requirements.
Measured output impedance exceeded 1.3 MΩ below 200 kHz and reached 250 kΩ up to 1 MHz.
Experiments on a biological RC model yielded low mean errors of 0.192% for impedance amplitude and 0.139° for phase.

Conclusions:

The developed FPGA-based current source is wideband, biocompatible, and highly precise.
It shows significant potential as a crucial sub-system for advanced multi-frequency electrical impedance tomography applications.